Message
Re: [colorvision_group] Re: Using Printfix spectro for measuring other things.
2007-02-27 by CDTobie@aol.com
In a message dated 2/27/07 2:34:08 PM, rlphoto@... writes:
Thanks CD, I managed to find on the web the lab values of all the
munsell chips from the RIT site. There are 6 vertical collums of data.
HVC XyY. Can I just copy and paste into excel? It would take me a year
to enter this data by hand.
Sure, but you need to have certain Excel (and math) skills... and the values you have are XyY (or more likely xyY), which can be converted to Lab from there, but are not automatically in Lab. So you would need to create an xyY (or whatever) to Lab formula, drag it down to all rows, and it would spit out three more columns, of Lab values for each chip. My theory was that you would just measure your chips in order, and it would give them real, measured, Lab values, rather than theoretical, batch values.
And you aren't done there... you need to create a search function that will find the closest match in all three columns (Lab) for your input value. Its easy to search one column for the closest single value, but its more complex to search three of a calculated least difference. It would be simplest to subtract your values L, a, and b compents from each, and add the absolute value of the three results together, and search for the smallest total: but calculating the DeltaE94 for each from your input value, and finding the smallest DeltaE94 would be the best method. Sorry you started this yet?
C. David Tobie
Product Technology Manager
ColorVision Business Unit
Datacolor Inc.
CDTobie@...
www.colorvision.com
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